Radiation polymerizable compositions containing organopolysiloxanes having silicon vinyl groups and organopolysiloxanes containing mercaptoalkyl constituents are described, for example, in U.S. Pat. No. 3,816,282 to Viventi.
U.S. Pat. No. 4,064,027 to Gant also describes a composition containing a mercaptofunctional siloxane and a vinyl containing siloxane which is curable by radiation.
U.S. Pat. No. 4,070,526 to Colquhoun et al discloses a radiation curable composition containing a mercaptoalkyl substituted polydiorganosiloxane fluid and a vinyl monomer such as an acrylate and a photosensitizer.
U.S. Pat. No. 4,606,933 to Griswold et al discloses acrylate-functional silicone compounds which are prepared by reacting acrylate-containing compounds with an aminosilane or an aminofunctional polysiloxane in the presence of a base catalyst.
U.S. Pat. No. 3,532,729 to Cekada et al discloses the preparation of siloxane emulsions by reacting a mercapto organosiloxane emulsion with a polymerizable olefin such as an acrylate or methacrylate in the presence of a free radical catalyst.
In contrast to the method described in Cekada, the present invention reacts an acrylic and/or methacrylic compound having at least two acryloyl groups or methacryloyl groups or mixtures thereof per molecule with a thiol-functional organopolysiloxane having one or more thiol (SH) groups per molecule in the presence of a base catalyst to form compositions having acrylic and/or methacrylic functionality. These compositions can be cured in the presence of a radiation source, or in the presence of heat.
It is, therefore, an object of the present invention to provide .alpha.,.beta.-unsaturated carbonyl-functional polysiloxanes. Another object of the present invention is to provide .alpha.,.beta.-unsaturated carbonyl-functional polysiloxanes having at least one acryloyl or methacryloyl group per molecule. Another object of the present invention is to provide .alpha.,.beta.-unsaturated carbonyl-functional polysiloxanes containing acryloyl or methacryloyl groups, which are very reactive under radiation conditions. Still another object of the present invention is to provide .alpha.,.beta.-unsaturated carbonyl-functional polysiloxanes in which the acryloyl or methacryloyl group is bonded to the silicon atom via a thioether group. A further object of the present invention is to provide a process for preparing .alpha.,.beta.-unsaturated carbonyl-functional polysiloxanes. A still further object of the present invention is to provide .alpha.,.beta.-unsaturated carbonyl-functional polysiloxanes which are curable in the presence of heat and/or a radiation source.